Fabrication and characterization of Si/ZnO branched heterojunction structures

We have fabricated branched heterojunction structures by growing horizontal ZnO nanowires (ZnONWs) on vertical Si nanowires (SiNWs). The SiNWs were fabricated by chemical etching of Si wafers, while the ZnONWs were grown in solution by an electrochemical process. Structure and electrical properties of the branched NWs studied by SEM, XDR, and electrical measurements. The SEM images show that 3-D branched SiNWs with ZnONWs branches were successfully grown. Due to its light trapping effect this special structure may have applications in photovoltaic devices. Solar cells based on the branched structure were also fabricated and tested. We found that their cell performance depends on the length of both the SiNWs and the ZnONWs, as well as the thickness of ZnO seed layer.